Tread stitcher for tire machine assembly



Aug. l0, 1954 H. H. DElsT TREAD STITCHER FOR TIRE MACHINE ASSEMBLY 5 Sheets-Sheet l Filed DGO. 3, 1951 H. H. DEIST TREAD STITCHER FOR TIRE MACHINE ASSEMBLY Alug. 10, 1954 5 Sheets-Sheet 2 Filed Deo. 3. 1951 m QN@ v JNVENToR. HF/F/f f77-.51.21757 BY Aug. 10, 1954 H. H. DElsT 2,585,909

TREAD STITCHER FOR TIRE MACHINE ASSEMBLY www5 Aug. 10, 1954 Filed Deo. 5, 1951 H. H. DEIST TREAD STITCHER FOR TIRE MACHINE ASSEMBLY 5 Sheets-Sheet 4 INVENTOR.

Patented Aug. 10, 1954 TREAD STITCHER FOR TIRE MACHINE ASSEMBLY Herbert H. Deist, Akron, Ohio, assi-gnor to The Firestone Tire & Rubber Company, Akron, Ohio, a corporation of Ohio v Application December 3, 1951, Serial No. 259,589

- l 'This' invention relates to tire building machines and more particularly to improved tread stitching devices associated with such machines.

' Tread stitchers usually comprise a pair of discs -or wheels which are rolled against a tire after it is built'on a building drum. The discs contact the tire in tightspiral paths leading from the center of the tread outwardly to the bead portions, the spirals resulting from opposite traversing movements of the discs while the drum is rotated. In this manner much of the air which is trapped within the body of aV tire is expelled, and a rmcohesion ofthe various elements of the tire is secured. Y It is desirable in the stitching operation to exert la considerable stitching force upon the tread portionsbut a considerably smaller stitching force upon the side walls. the tread portions are thick and much of the stitching force is absorbed in compression of the tread before it is transmitted to the tread-carcass interface, While'the side walls are relatively thin and do not require much force in order to obtain thev desired-results. 'In addition, if excessively large stitching forces are applied to the side walls, there is a tendency to push the material ahead ofthe stitcher blades and distort the sidewalls. Heretofore, the force which the stitcher exerts 'upon the tire has been produced either by mechanical springs or by means of a hydraulicpis- :ton and cylinder arrangement. In neither case is itpossible to obtain the [desired predetermined loads upon the stitchers.

Where mechanical springs are used, the force exerted by any of the springs can'rfollow only a single, fixed, load-deflection curve which-is peculiar to that spring. s As a result,- there is'no control over. the stitching forces, and no possibility of, adjusting those forces for different tires. r ThereY is no assurance that-,the load-.deflec- .tion curvegkotfthe spring will be suitable for stitchingra single tire much -less a Whole range of 2 Claims. (Cl. 154-9) This is necessary because tire contours and sizes. Where air cylinders are used to load the, stitchers, the forces exerted-Will be substantially constant .for any given air pressure withthe forcesexerted upon the sidewalls being equal to those exerted upon the tread. As pointed. out above, vit is unnecessary and undesirable to apply heavy forcs to the side Walls of a tire.` Moreover, an ,airacylinder vwill not follow the same load-deflection curve. in repeated trials,

and hence it cannotbe accurately calibrated.

` The forces'exertfedby'air cylinders are variable because of frictionwithin the'jcylinders, becauseV of leakage, fa'rldbeoause the cylinderstend to stick if there is any lateral force exerted upon the 2 stitchers; moreover, air cylinders require excessive maintenance. 'a

All of these difficulties and disadvantages are overcome by providing a stitcher in which a bellows arrangement is used to produce the required forces. The bellows will exert uniform and equal loads on each of the stitcher discs, and the loads may be accurately determined and maintained simply by controlling the air pressure which op-j crates the bellows. There is no tendency for the bellows to stick, and the bellows are free from the problem of leakage and friction. y

Bellows, moreover, have load-deilection curve which are desirable for use in stitching tires, for the exerted force falls off substantially as the bellows are extended so that the side Walls of the tire are subjected to considerably less stitching pressure than the tread. Moreover, the load-defiection curve for the bellows will vary with the air pressure within the bellows so that a whole set of load-delection curves corresponding to a set of different air pressures can be obtained. A11 that is necessary in stitching tires is to select the airpressure which has the load-deflection curve capable of the desired stitching performance. The stitching forces may be controlled independently of the diameters of the tire building 'drums with which the stitchers are used and independently of the tires being stitched merelyv by selecting the proper working air pressure.

The general object of the invention, therefore, is to provide tread stitchers which are loaded by means producing accurately predetermined loads. Another object of the invention is Yto provide pneumatic stitcher means having a set of loaddelection curves corresponding to a set of diierent air pressures applied to the means.' Another object is to provide loading means for stitchers which are rugged and serviceable, which have a 10W initial cost, which may be' easily and cheaply installed, and which require -a minimum of maintenance. Further objects and advantages of the invention will appear from the following description of'a preferred form of the invention, reference being had to the accompanying drawings in which: ,1

Figure 1 is a front elevation showing the essential parts of the invention in lassociation with a tire buildingfdrum; i Figure 2 is a top elevation 'ofthe apparatusk of Figure 1 showing in addition the'driving mechanism which produces the traversing movement of thestitchers; l j vFigure 3 is a View vpartly in section showing the manner in whichl the stitchers are given vertical adjustment, the section being taken in the plane indicated by the lines 3--3 of Figure 2;

Figure 4 is a section taken in a horizontal plane indicated by the lines 4--4 of Figure 3 showing further details of the manner in which the stitchers are mounted; and

Figure-15. is ra=chart showin-gv the relation between bellows; extension and "the k'force-'exerted by the bellows, this relation being shown for a number of different operating air pressures with+.

'Thestitchers I0 `areurged into-contact'against f.

the. tire I3- throughout their traversing movements-by bellows I4 `whichhave a predetermined airupressuref therewithin.` Atr the end. of` the traversing movement, the air: pressure isV reduced; to withdraw the stitchers-from. contact with the tire, .and the vstitchers are then returned to theirfinitia-l .position beneath the center =.of. thebuildng drumin readiness 1.for their nexttraversing stitching movement.. As noted `above;` thediscs contact'r the tire I3 in tight spiral paths-and. thus .compress the. elements of the-'tire---together in acoherent structure.

Thecarriages I'I- on which the stitching discs are mountedrare-supported. inia manner which enables them to support Athe stitching discs and atxthesame `time haven-free, traversing movementa. `Thus,. each carriage 'comprisestv a body portion.` I 5` which isV supported by rollers 64 which rest upon 'the rails. II of a. supporting frame indicated generally at I8. Four such rollers are provided. for-each carriage, see Figure4, toprovide adequate'support; The ilanges IB of the rollers- .have rollingr contact with the sides-f. of rails;v Iz'I'to hold: the carriages securely vagainst movement in "a: direction `at right anglesto the axisz of v`tlie.:building drum..

'Thertraversingf movementuof: the @carriages is -providedby a'-.central jack' shaftzl]l whichiis jeurnaledfasfat 22 anclz23-in the frame IB... The

jack` shaft. hasLtwo:threaded portions i241 and ,Z5

which are? opposite Ainrpitch a and .which .cooperate respectively withv threaded .nuts I26"fand12.11'of likef-ipitch-which-are secured to the "carriages, see Figurex 4; Thelshaft Z'Iis driven by appropriate means-which as illustrated includes the; reversing motorZB and the gears 29' and.3l. When the-motor isudriven in one direction, the two carriages will be' moved away fromeach other by theffopposite threaded portionsY 24 and .2.5; land vii-lien4 the motor isrreverseol; the carriages` will move together to the position of Figure 1.

.The stitcherdiscs I0 are mounted-on the carriages'. II. in a ,manner to minimize; the lateral instability of the bellows I4. Thus; it will` be noted-.from Figures 1-and 3 that the dises are journaledfon axles 32 which are supported by arms..33.which are pivoted asat 3ft-to the head portions 35 of the carriages. The bellows. I4 are mounted on .the carriage...heads 35.,.in-.the-mannershewn ^in Figure withthe bottom.. plates 4 36 of the bellows secured to the top of the heads and with the top plates 31 pivotally connected at 38 to the supporting arms 33 by brackets 39. When air under pressure is introduced into the bellows I4 through exible conduits 42, the bellows will expand and rock the arms 33 upwardly in aV counter-clockwise"xnm'ement:as viewed in Figure.-3"to::bring the-stitcherrdiscs Vforcibly into contact with the tire. When the air pressure in the bellows is released, the bellows will contract and brngthe stitcher discs downwardly out of lcontactwith'the*tire. The conduits 42 are nexible and of suflicient length to permit the stitcher carriagesttoimaketheir full traversing movement,

' '.fsee Figurer-.21.v

'The-head" portions 35 of the carriages can be vertically adjustedwithin wide limits to enable the stitcher to be used with building drums of widelyvarying diameter. This vertical adjustability compensates for the limited extensibility of the-bellows?. although desired, thee bellows may. have .enough .sections to provide the-required expansion. Infaddition, the-.vertical adjustment of.- the bellows will :bring 'the .operating range' of the-:bellows within the l desirable yportion of.: the load-deflection; curvefior. agiven airr pressure. Thus, .in Figure 3; the.` apparatusfisshown for use-with a tire.buildingdrumfofrlarge diameter. IfA the` same apparatusl were to: be usedt'with la drum of smallery diameter, thestitchingihea'ds: 35 would be raised. upwardlvto-enable'the bellows to exert .the-desiredpforcer without-f reaching their limitz of extension: While anyvmanner of .wertical adjustment may be provided, :that illustrated in' FigureJSr has been found to be: practicable. As shown, :the heads' 35Y have ldepending.` screws 43s whichr are' received within bores III!` of. the carriages, 'and the; Vcarriageshave nuts'ril` cooperating with. screws'f43. In" order tovraise a stitchingl head',- the.: head Yist :rotated bodily' 360 an'dzinlso doing is liftedatfdistancev depending onfthe.. characteristics of its liftingfscrew; In order-Ito hold'theheadsagainstlateral movement'. thesscrews have.v cylindrical extensionsf -4 fwhich lravefa` snug, slidingfitiwithin `the bores-.M ofi the carriages'. i

The heads:- are secured; against 'fac'cidentalrotation by detentsr 41', each detent comprising a pin" 41872 which extendsI within a.: vertical` Vgroove 48S inthe screw 43 tor'lock' itfinposition. The pin` isA urgedl into locking position byaa coil "spring Silffconiined betweenV adetent Ahousing '5?I'fan`d -a washer 52 secured to the lpi-n; The 'detents IFI must, of course', be pulled` outwardly 'clear of theA lscrewsfwheni the I stitching" heads are given their vertical adjustment.v

'The arrangement is simple in construction'and operation. When lthe operator' has'ln'i'shedbuil'cling a tire I3 -on the drum and is ready for stitching, hejopera-tes a switch whichpassesvair under theV desired pressure into Vthe bellows.- arms"33 swing upwardly; and the-discs I0* are pressed into contact with-the tire with the `full force of the bellows. It is possible' to determine what stitching force is 'exerted upon the tire at any instant by reference-toa calibration chart suchas thatshown in Figure '5 in' which isV shown .a set of. load-.deflection curvesfcr .a particular bellows', .there being an individual curve for each'air'pressure within the" bellows. Irrthe .chart 'the exertedforce' is plotted' as the abscissa and the vbellows 'extension as ordinate for each air. pressure in the bellows. vThe fact tliatv the'bellowsv has such a rangeofjadjustment provides, great 'flexibility in the stitchingpperation, for the vertical adjustment of the bellows bodily enablesa particular range of bellows extensibility to be obtained for any operating air pressure. The forces are virtually unmodied by the effects of friction, leakage, etc. and will remain uniform and accurate under all normal conditions.

A short time after the discs contact the center of the tire tread, the motor 28 is energized to drive shaft 2| and the carriage I I in their stitching movement. When the carriages reach the end of the drum, one of the carriages will trip a limit switch 53, see Figures 2 and 3, and terminate the outward movement of the carriages; the air pressure in the bellows will be released; the stitcher arm 33 will drop down; and the motor 28 will be reversed to drive the carriages back to their original position. When the carriages reach their original position, a second switch 54 will be tripped, and the apparatus will be ready for its next cycle of operatiom Reverting once again to Figure 5, it will be seen that the extension of the bellows in inches, indicated as air spring length, is plotted against the load in pounds exerted by the bellows alone, entitled air spring compression load. This relationship is plotted for various air pressures within the bellows. The chart is used as follows. For example, if experience has shown that a stitching force of about 275 pounds is desirable for the tread and a stitching force of about 150- 160 pounds is desirable for the sidewall, such stitching loads can be obtained by using an air pressure in the bellows of 20 p. s. i. as indicated by the dotted lines in the chart; the actual loads of 160 and 275 being obtained by virtue of the ratios of lever arms in the apparatus which reduce the bellows force in the ratio of 2: 1. Such loads are obtained when the tread is about an inch thicker than the sidewall. Ifthe same loads should be desired for a tire in which the tread is only about 1/2 inch thicker, 30 pounds of air pressure can be used, and the range of bellows extension used would be from about 4.6 to 5.2 inches. Similar variations in thickness can be accounted for by selecting different air pressures. Again if a tread stitching pressure of 400 pounds and the same sidewall stitching force of 160 pounds should be desired, a pressure of 35 p. s. i. would be selected, and the operating range of the bellows extension would be from about 4.2 inches to about 5.3 inches. It will be apparent from the chart that the use of a bellows affords a flexibility of performance not obtainable by other means.

Various modications are, of course, possible within the scope of the invention. For example,

instead of the rollers I6 and rails I1 which support the carriages, the carriages may be supported by shoes sliding on appropriate ways; and instead of the Vertical adjustment of the stitching heads alone, the Whole apparatus may be bodily adjusted in vertical position in order to adapt the apparatus to various size drums.

Further modifications will no doubt occur to those skilled in the art within the scope of the invention, the essential features of which are summarized in the appended claims.

What is claimed is:

l. A tire building machine comprising a tire building drum, a stitching apparatus frame, a pair of carriages supported by said frame, means to move said carriages simultaneously in opposite directions along said drum, a stitching head mounted on each of said carriages, an arm pivoted to each stitching head at one end of each of the arms, each arm carrying at the other end of said arm a stitching disc journalled for idling rotation, each said arm being movable in an arcuate path about its pivot, and a fluid-pressureextensible, flexible-Walled bellows mounted on f each said carriage with one end of each bellows attached to its carriage and the other end of each said bellows being attached to its arcuately movable arm, each bellows when extended by uid pressure exerting a force to move each said arm in said arcuate path with respect to said carriage and to press said idling disc into contact with a tire on said tire building drum.

2. In a tire building machine, a tire building drum, a stitcher carriage mounted for movement relative to the drum, an arm pivoted to said carriage for arcuate movement with respect to said carriage and said drum, a stitching disc journalled on said arm remote from said pivot, and a fluid pressure-extensible bellows having one end thereof mounted on said carriage and the other end mounted on said pivoted arm remote from said pivot for moving said stitching disc toward and from said tire building drum in an arcuate path and for forcing said stitcher into contact with a tire on said drum.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,981,828 Shook Nov. 20, 1934 2,161,117 Wikle June 6, 1939 2,208,539 Brown July 16, 1940 2,224,821 Humphrey Dec. 10, 1940 2,381,379 f Stevens Aug. '7, 1945 2,382,958 Burgoine et al Aug. 21, 1945 2,581,933 -Stevens 1 Jan. 8, 1952 

